1. Field of the Invention
The present invention relates to an apparatus and a method for measuring contamination of a developer of a printer, and more particularly, to an apparatus and a method for measuring the concentration and contamination of a developer of a printer using data obtained from the developer under various conditions. This application is based on Korean Patent Application 98-44997, which is incorporated by reference herein for all purposes.
2. Description of the Related Art
FIG. 1 is a schematic view of a typical liquid type color printer. Referring to FIG. 1, a printer using a developer includes a reset apparatus 15, light scanning units 16, developing units 30, a drier 18, and a transfer apparatus 20, adjacent to the circulation path of a photosensitive belt 14 around a plurality of rollers 11, 12 and 13.
The reset apparatus 15 includes an exposure apparatus 15a radiating beams to the photosensitive belt 14 to remove an electrostatic latent image, and an electrostatic charge unit 15b for charging the photosensitive belt 14 to a predetermined electric potential. Reference numeral 39 denotes a waste tank for collecting waste developer.
The four light scanning units 16 scan information of yellow Y, magenta M, cyan C and black K, respectively, and the four developing units 30 supply developers of Y, M, C and K to the photosensitive belt 14, respectively.
The developing unit 30 includes a developer supply unit 32 supplying a developer, and a developing bath 31 collecting developer dropped from the photosensitive belt 14 and resupplying the collected developer to the developer supply unit 32. The developing bath 31 includes a developing roller 36, a brush roller 37 for removing developer from the developing roller 36, a squeeze roller 34 for separating a liquid carrier regardless of image forming, from the developer supplied to the photosensitive belt 14 and a plate 35 for collecting the carrier flowing through the squeeze roller 34 to the developing bath 31.
The developer stored in the developing bath 31, the liquid carrier (norpor; N) of the solvent in the developer supply portion 38, and a toner of a developing material or a developer of high concentration in the developer supply portion 38 can be supplied to the developing supply unit 32. The developer stored in the developer supply unit 32 is supplied between the developing roller 36 and the photosensitive belt 14 by driving a pump.
During printing of a liquid type printer, the light scanning unit 16 scans light beams on the photosensitive belt 14 circulating past the reset apparatus 15. An electrostatic latent image is formed on the photosensitive belt 14 by the scanned light, and the electrostatic latent image is developed by the developer supplied from the developer supply unit 32. A color image is formed on the photosensitive belt 14 by the light scanning units 16 scanning light beams of different color information, and the developing units 30 developing an image by a developer of a corresponding color. Most of the liquid carrier of the developer supplied to the photosensitive belt 14 from the developing units 30 during the development, regardless of the image formation, is returned into the developing bath 31. The color image formed on the photosensitive belt 14 by a toner of the developing material is first transferred to the transfer roller 21, having a portion thereof engaged to the photosensitive belt 14, via the drier 18 for removing liquid carrier remaining on the photosensitive belt 14, by movement of the photosensitive belt 14. The image on the transfer roller 21 is then transferred to a sheet of paper 23 by rotation of the transfer roller 21 and a fixing roller 22 where the sheet 23 is inserted and moved forward.
Meanwhile, in the above-described printing operation, when toner attached to the photosensitive belt 14 during the development partially remains on the photosensitive belt 14 without being transferred to the sheet 23, the toner may drop into the developing bath 31 of the developing unit 30 during circulation of the photosensitive belt 14. Particularly, if black toner contaminates the developing bath 31 having yellow developer through the photosensitive belt 14, the appropriate color cannot be produced. Thus, contamination of developer caused by a developing material of one color mixing with the developing bath 31 of another color must be checked, and when the contamination exceeds an allowable range, the developer must be appropriately replaced.